This invention is concerned with a mould arrangement for use in a cyclicly operating glassware forming machine, the arrangement comprising a mould comprising a bottom plate defining a bottom portion of a cavity of the mould in which molten glass is moulded in the operation of the machine, and two side portions defining side portions of the cavity, each side portion being movable, in a cycle of operation of the machine, to a first position thereof, in which it engages the bottom plate and the other side portion to co-operate in defining the mould cavity so that moulding can take place, and to a second position thereof, in which the side portions are separated to allow moulded glass to be removed from the mould cavity, the side portions also defining cooling passages through which air can pass to cool the side portions, each cooling passage having an entrance in a bottom surface of a side portion and passing upwardly through that side portion.
The invention is also concerned with a bottom plate for a mould arrangement for use in a cyclicly operating glassware forming machine, the plate comprising a base portion and a central portion which projects upwardly from the base portion, the central portion having an upper surface arranged to define a bottom portion of a mould cavity and side portions which form recesses arranged to receive complementarily-shaped portions of side portions of a mould which are arranged to define side portions of the mould cavity and are movable, in a cycle of operation of the machine, to a first position thereof, in which they engage the bottom plate and each other to co-operate in defining the mould cavity so that moulding can take place, and to a second position thereof, in which the side portions are separated to allow moulded glass to be removed from the mould cavity, the side portions also defining cooling passages through which air can pass to cool the side portions, each cooling passage having an entrance in a bottom surface of a side portion and passing upwardly through that side portion.
In a glass container manufacturing machine of the so-called "individual section" type, a number of container making units or sections are arranged side by side, are fed with glass from a common source, and feed their output to a common conveyor. Each of these sections has at least one parison mould in which a parison is formed from a gob of molten glass delivered to the mould, and at least one blow mould in which parisons are blown to the shape of the container. The blow mould forms part of a mould arrangement as described above and comprises a bottom plate as described above.
Since the moulds of an individual section type machine absorb heat from the glass at a rate which is faster than the heat can be dissipated to the surrounding atmosphere without additional cooling, such moulds are supplied with cooling means which cool the mould so that it remains at a substantially constant average temperature during successive operations of the machine. Because the sections of an individual section type machine need to be close together, for reasons of glass supply, only very limited space is available around the mould for the provision of cooling means. One solution to this problem is to feed cooling air through the frame of the machine section to a vertical cooling stack which is provided with nozzles which direct the air on to the outside of the mould. This solution, however, has the disadvantage that the supports supporting the side portion of the mould interfere with the flow of air to the mould and also that it is difficult to provide differential cooling around the mould as is desirable. Furthermore, such cooling stacks are a source of undesirable noise. In another type of cooling means, cooling air is supplied through the supports of the side portions of the mould to a chamber around the mould. This type has the disadvantage that a seal has to be provided between the supports and the side portions of the mould, causing delays in changing moulds and increasing the cost of the mould. It is also difficult to provide differential cooling around the mould. Attempts have also been made to cool moulds by passing cooling air through passages in the side portions thereof. Examples can be found in U.K. Patent Specification No. 1,337,292 and U.S. Pat. No. 4,251,253 (FIGS. 10 to 12). In these arrangements, pipe connections are involved between the supports and the mould portions thereby causing delay to mould changes and increasing the cost of the moulds. Furthermore, in these arrangements, the cooling air makes sharp changes of direction in the mould so that considerable resistance to air flow is created requiring the use of high pressure air to achieve adequate flow. The use of high pressure air is undesirable because of the expense involved. Furthermore non-uniform air flow is created distorting the cooling effect and making it difficult to predict. Thus, it becomes difficult to predict where to position the cooling passages to achieve the optimum cooling effect. If the passages are not initially correctly positioned, the cooling effect can be adjusted by inserting plugs or insulating sleeves into the passages but this is a time-consuming trial-and-error method because the effects of the plugs and/or sleeves are again hard to predict.
In the specification of European Patent Application No. 83304985.1 (Publication No. 0102820), there is described a mould arrangement in which a plenum chamber extends beneath the first or the second position of each side portion of the mould and has one or more exits which open upwardly and communicate, when the side portion is above the plenum chamber, either directly or through vertical passages in the bottom plate with the entrances of the cooling passages in the side portions so that air is supplied to each cooling passage at substantially the same pressure, the plenum chamber also having an entrance connected to air supply means operable to blow air into the plenum chamber. This arrangement provides cooling means in which the above-mentioned disadvantages of previous cooling means are overcome. However, this mould arrangement is not applicable to existing bottom plate supporting mechanisms, requiring replacement of said mechanism by a mechanism of a different design.
It is an object of the present invention to provide a mould arrangement in which the advantages of the arrangement described in the aforementioned European Patent Specification are achieved and in which an existing bottom plate supporting mechanism can be used.